The tire-road friction coefficient is a dimensionless value indicating the friction qualities of the tire against the friction qualities of the road. Many vehicle control systems, including but not limited to electronic stability control systems and anti-lock brake systems, utilize a tire-road friction coefficient when determining how to control the various components of the vehicle. The tire-road friction coefficient changes with differing tires and differing road conditions. For example, the tire-road friction coefficient will be greater on dry pavement than on wet pavement for the same tire on the same vehicle in the same operating conditions. Because the tire-road friction coefficient is continuously changing, the vehicle controller must continuously monitor and/or calculate the road-tire friction coefficient for the various control systems to use.